[SOLVED] Multiple Domain in one server with common GAL

I have installed Zimbra 6.0.1 Open Source on RHEL 5 and created 3 domains for which I want to receive email, domain1.com, domain2.com and domain3.com
and created 5 users in each domain, total 15 users together. Whenever I am composing the mail using one users login and click "TO" and select the address, it shows only the domain's users GAL whom it belongs to. ( In other words, only the domain1.com's address list while login as user@domain1.com ). Can anyone give some idea how to get all the addresses of all three domain in GAL?

You have been a huge help in my Zimbra adventures.. I have a quick question.. I have 15 domains and around 1,000 users spread across those domains on around 800 computers... If I merge the GAL on all domains.. How much will the access time be effected?